Coal-drill.



No.. 662,646. Patented Nov. 27, |900.

M. vHAIDSOCG. CUAL DRILL.

(Application led Feb.v 7,

(lo Model.)

L l z l I 4 sin rares .artnr risica.

MARTIN HARDSOOG, OF OTTUMWA, IOWA.

COALWDHILL.

SPECIFICATION forming part of Letters Patent No. 662,646, dated November27, 1900. Application filed February 7, 1900. Serial No. 4,351. (Nomodel.)

To all whom t may concern.-

Beit known that I, MARTIN HARDSOCG, a citizen of the United States,residing at Ottumwa, in the county of Vapello and State of Iowa, haveinvented certain new and useful Improvementsin Coal-Drills, of which thefollowing is a specilication.

My invention relates to that class of drills which are adapted to beused in boring holes in coal, and particularly to the drill proper, aswill be more fully hereinafter set forth.

The object of the invention is to provide a simple, economical, andefficient coal-drill; and the invention consists in the features,combinations, and details of construction hereinafter described andclaimed.

In the accompanying drawings, Figure lis an elevation of a coal-drillconstructed in accordance with my improvements, showing'a portion of thedrill as it appears while being formed; and Fig. 2, a longitudinalsectional View ofthe drill as it appears when constructed in accordancewith my improvements.

In constructing a drill in accordance with myimprovements I makea longmetallic strip in cross-section resembling the cross-section A of Fig.l, such strip having a substantially il-shaped projection @thereonlocated, preferably, near one edge. The strip is cut away to one-halt'its thickness on the .inner face of one edge and the exterior face ofthe other edge, forming on the inner face an overlap ct/ with a squareshoulder and an end edge and forming on the outer face an underlap a2with a square shoulder and an end edge, each the counterpart of theother, so that when the strip is coiled in a spiral the two laps tagainst each other to leave a smooth continuous inner face and a smoothface on the eX- terior between the triangular or V-shaped rib or flangea, the two overlaps engaging, as shown particularly in Fig. 2. Y

To form the drill, the strip A is taken and rolled around a solid rod ortube in a spiral or helical manner, the shouldered exterior and interioredges overlapping each other, producing, as shown in Fig. l, a completehollow drill having a spiral or helical cutting and elevating rib orprojection ct thereon.

In use the rib or projection a is sharpened at as, so that it removesthe coal, so as to form an annular bore the width of the thickness ofthe tooth and body of the drill, and as the material is cut away fromthe body of coal it is elevated by this spiral or helical rib orprojection, which acts as a conveyer or elevator to force the materialout at the entrance to the hole. At the same time a core is left in thehole of a diameter equal to the tubular axial opening A in the drill. lnorder to extract this core, the drill must be extracted, say, when ithas drilled to a depth of about two feet, and the core is broken oit'and removed from the hole.

rlhe principal advantages due toadrill constructed in accordance withrnyimprovement are that the drill is simple and economical tomanufacture, being made from a strip of metal strengthened and maderigid by the shouldered laps when spirally wound on itself,Y may bealways kept sharp b v merely grinding the projection thereof at a3,thereby dispensing with the necessity of sending it to a hlacksmithsshop, and finally the drill acts to clean the hole rapidly andefficientlyof the loose material.

I claim-- l. A drill made from a strip of metal provided on its outerface with a continuous 1ongitudinal triangular-shaped rib and having itsedges formed to engage one with the other, for the winding of the stripon itseltl to bring the edges into engagement and form .a hollow bodyhaving a smooth interior for the drill and to cause the Vrib to formacontinuous elevating-spiral on the exterior face of the body,substantially as described.

2. A drill made from a strip of metal cut away at its edges to formshouldered laps and provided on its outer face with a continuouslongitudinal triangular-shaped rib, for the winding of the strip onitself to bring the shouldered laps into engagement and form a hollowbody having a continuous smooth interior for the drill and to cause therib to form a continuous elevatingspiral on the eX- terior face of thebody, substantially as described.

3. A drill made from a strip of metal cut away on its interior face toform a shouldered overlap and cut away on its exterior face to form ashouldered underlap and provided on IOO bod)1 and permitting thesharpening of the drill by grinding the rib, substantially as described.

MARTIN HARDSOCG. Witnesses:

L. K. KooNTz, C. R. ANDERSON.

